When summer turns fierce, even sun-lovers can flag. A little temporary shade can be the difference between a thriving bed and a sulking one. Here’s a simple, practical guide to reading the signs, choosing the right cover, and setting it up so plants keep growing rather than merely surviving.

The quick take

If daytime highs sit above ~32 °C for several days, nights stay warm, leaves are wilting by lunchtime and not bouncing back by dusk, or you’re seeing scorch or fruit sunscald, add afternoon shade until the heat eases. Prioritise seedlings, shallow-rooted crops, containers, newly planted shrubs, and any plant that prefers “cool roots”.

How to spot plants that need shade now

  • Persistent wilt: foliage collapses from late morning and does not recover fully overnight.
  • Scorch: brown, crispy leaf edges or bleached patches.
  • Sunscald on fruit: pale, papery areas on tomatoes, peppers, cucumbers and squash.
  • Blossom or fruit drop: flowers aborting during hot spells.
  • Slow growth despite water: the plant is shutting down to cope.

If two or more of the above show up during a hot, dry run, give them relief.

Choose the right shade (and how much of it)

Not all shade cloths are equal. The percentage is how much light they block.

  • 30–40%: most veg and herbs in full sun, tomatoes and peppers during heatwaves, brassicas that are bolting, lettuces you’re trying to keep going a bit longer.
  • 40–50%: cucumbers, courgettes, aubergines, hydrangeas and other moisture-hungry ornamentals during extremes; hardening-off seedlings.
  • 60–70%: ferns, hostas, shade annuals, delicate houseplants summering outdoors; emergency triage during record highs.
  • 70–80%: short-term rescue only or for genuinely shade-loving collections.
  • Fabric choices: knitted polyethylene shade cloth is light, doesn’t fray and copes with wind. For short stints, light-coloured burlap, old net curtains, or a clean bed sheet on canes also work. Avoid dark tarps that trap heat.

When to deploy shade (timing matters)

  • Afternoon, not all day: the harshest sun is typically 12:00–16:00. Aim to keep morning light for photosynthesis and switch to dappled protection after midday.
  • During heatwaves: keep shade in place continuously and ventilated until temperatures moderate, then remove or roll back.
  • After pruning or storm damage: sudden extra light can scald previously sheltered leaves and fruit; shade temporarily while tissues toughen.

How to set it up in beds and borders

  • Hoop tunnels: push flexible hoops into the bed edges, stretch shade cloth over and clip. Leave the ends open for airflow.
  • A-frames or fence panels: lean a light trellis or panel on the west side to cast an afternoon shadow. *
  • Overhead sails: a simple triangle of cloth tied to stakes gives even coverage over mixed plantings.
  • Keep the peak high for air movement.
  • Spot shields: for individual shrubs, use three canes to form a teepee and drape cloth so it shades from the sun’s side, not the top.
  • Airflow rule: if leaves are touching the fabric, raise it. Trapped heat causes more stress than sun.

Container and patio plants

Pots heat up fast. Move what you can to dappled light under a tree, pergola or south-west eave. For heavy tubs, add a freestanding parasol or clamp a small sail to a railing. Double-potting (slipping the nursery pot into a larger decorative pot with a few centimetres of air gap) helps insulate roots.

Watering, mulch and feed: make shade work harder

  • Water early and deeply so roots have reserves before heat builds. Check moisture with a finger 5 cm down; don’t guess.
  • Mulch 5–7 cm around plants to keep roots cool and slow evaporation. Keep mulch a palm’s width from stems.
  • Hold the high-nitrogen feed during extremes. Pushy, sappy growth scorches easily; resume balanced feeding once the heat breaks.

Greenhouses, tunnels and windowsills

  • Fit external shade netting or paint on removable shading (lime/kaolin/shade paint) before the hottest spell.
  • Prop doors and vents wide. A small circulation fan dramatically lowers leaf temperature.
  • Indoor windowsill herbs can be shielded with a sheer voile during the hottest hours.

Crop and border design that self-shades

Plan taller, heat-tolerant plants to the west or south-west of lower, tender crops so they cast an afternoon shadow. Classic pairings: tomatoes sheltering lettuce, sunflowers sheltering spinach, sweetcorn sheltering coriander. In borders, a light-canopied small tree can protect hydrangeas and woodlanders beneath.

A simple heatwave playbook

  1. Prioritise: seedlings, transplants, containers, shallow-rooted leafy crops, hydrangeas and anything newly planted.
  2. Shade the west: target from midday onwards.
  3. Soak, then mulch: water at dawn, mulch immediately.
  4. Ventilate: all covers must breathe.
  5. Ease off: pause pruning, repotting and fertilising until the spell passes.
  6. Remove gradually: roll back shade in stages over two to three days to avoid shock.

Common mistakes to avoid

  • Smothering plants with non-breathable plastic.
  • Shading all day for weeks, resulting in leggy, low-energy growth.
  • Letting cloth flap and rub foliage in wind; secure with clips or ties.
  • Forgetting the soil: no amount of shade fixes dry roots.

Quick FAQs

Will shade reduce yield?
Short, targeted afternoon shade during extremes preserves flowers and fruit set. That usually increases total yield versus letting plants stall or drop blossoms.

Can I leave cloth on in rain?
Yes, breathable shade cloth passes rain. Still check moisture beneath, as large leaves can divert water away from roots.

Do blue or green cloths cool more?
Colour has a minor effect compared with percentage and airflow. Prioritise the right density, then secure it well.